Feed tubing for centrifugal processes, particularly processes for separation of blood, are well known. One current centrifugal processing apparatus having such tubing is disclosed in Boggs U.S. Pat. No. 4,164,318.
Also, bowl-type centrifugal separation apparatus is well known, for example, the CELLTRIFUGE.RTM. cell separation apparatus sold by the Aminco Division of Baxter Travenol Laboratories, Inc. of Deerfield, Illinois.
In such systems as are described in the above Boggs patent, the feed tubing to feed blood or other mixtures to the centrifuge, and to remove separated components from the centrifuge, may be subjected in certain portions along its length to strongly abrasive forces on its exterior. Similarly, in other processes such as roller pumping, tubing may be used under abrasive conditions.
It is, of course, known that tubing may be coated with a silicone or other type of oil to serve as a lubrication aid. However, as the abrasion process continues, the oil may be rubbed away, following which the abrasion takes place at a rapidly increased rate, and may actually result in destruction of the tubing.
It is also known to the art to incorporate an oil such as mineral oil into a tubular structure, to provide an inherent lubricity as the mineral oil bleeds out of the structure. Such has been utilized in insertion nozzles for enema sets and the like. However, such a structure can be undesirable, particularly in the field of blood centrifugation or the like, because the lubricating oil in the tubular structure can leach into the bore or lumen or the tubular structure, and thus be transferred into the contents of the liquid materials flowing through the tubular structure.
In accordance with this invention, tubing is provided having high permanent lubricity, with silicone oil incoporated into the outer components of the tubing, while at the same time the bore of the tubing is defined by an inner portion which is substantially free of the silicone oil, so that the contents carried by the tubing are separated therefrom.
It is particularly considered surprising and unexpected that silicone oil can be homogeneously incorporated into tubing having an outer polyvinyl chloride plastic portion because of the known incompatibility between silicone oil and polyvinyl chloride formulations.